The present invention relates to a closure cap for the filling opening of a container, especially of a container containing operating fluids of a hand-held working tool driven by a combustion engine such as a motor chainsaw, a cutter, a trimmer etc., whereby the closure cap comprises a cylindrical base body with an outer thread that matches an inner thread of a filling opening. The base body is provided at one axial end with an angular flange having a seal whereby the angular flange and the seal engage the end face of the fill opening.
In hand-held working tools driven by a combustion engine the housing of the working tool includes containers for operating fluids. For example, in a motor chainsaw an oil container is provided from which the oil for lubricating the chainsaw is supplied into the guide groove of the guide rail. Furthermore, a fuel container for the combustion engine, in most cases a two-stroke engine, is provided. These operating fluids (oil, fuel, lubricant) of the working tool are provided in a container with fill openings which are to be closed by a closure cap in a fluid-tight manner. When the seal contained within the closure cap is undamaged and the closure cap is properly positioned and tightened with the required torque, a tight closure of the fill opening of the container over an extended service life is ensured.
Because of manufacturing considerations the thread of the fill opening is, in general, very short so that depending on the embodiment of the thread at the closure cap an improper threading of the closure cap into the fill opening may occur. Furthermore, because of the short thread a quick loosening of the closure cap must be avoided because excess inner pressure within the container may force the closure cap away from the opening during removal and the liquid contained within the container may spray. This is to be avoided in order to protect the operator as well as the environment.
It is therefore an object of the present invention to provide a closure cap for the operating fluid containers of a hand-held working tool provided with a combustion engine with which a safe tightening of the closure cap can be ensured and the removal of the closure cap under excess internal pressure can be avoided.